package com.lqk.facade;

/**
 * @author lqk
 * @date 2021/12/6 18:19
 */
public class Screen {
    private Screen(){

    }
    // 使用单例模式，静态内部类
    private static class ScreenInstance{
        private static final Screen INSTANCE = new Screen();
    }

    // 提供一个静态的公有方法，直接返回 SingletonInstance.INSTANCE
    public static Screen getInstance(){
        return Screen.ScreenInstance.INSTANCE;
    }

    public void up(){
        System.out.println(" Screen up ");
    }
    public void down(){
        System.out.println(" Screen down ");
    }
}
